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Authors
Abstract(s)
Nestes últimos anos tem-se observado uma maior preocupação por temas como o bem-estar físico e a
sustentabilidade ambiental, verificando-se uma maior procura, por parte da sociedade, de produtos mais
“naturais” e alternativas mais sustentáveis, nos quais se encaixam as bacteriocinas. São moléculas
versáteis de origem natural e ação direcionada, que dão cada vez mais provas de serem a resposta para
os desafios críticos da sociedade, desde a segurança e conservação dos alimentos até aos cuidados de
saúde e à sustentabilidade ambiental.
Neste estudo foram expostas a vários fatores nutricionais (meio de cultura) e ambientais (temperatura e
pH) 8 estirpes de Lactiplantibacillus (L. plantarum, L.sakei e L.curvatus) no intuito de provocar uma
situação de stress metabólico e assim produzirem bacteriocinas.
Inicialmente foi feita a pesquisa de genes produtores de bacteriocinas, por PCR. Todas as estirpes de L.
plantarum mostraram ter vários genes produtores, enquanto as estirpes de L. sakei não acusaram a
presença de nenhum dos genes estudados.
Os Testes de Sensibilidade a Antimicrobianos realizados revelaram algumas resistências à Tetraciclina
e Penicilina que determinam que estas estirpes serão potencialmente não seguras.
Em condições de crescimento de não stress, todas as estirpes revelaram ter um poder inibitório não
associado a bacteriocinas e após o crescimento em meios de cultura modificados, continuou-se a não
verificar uma capacidade de inibição proveniente das bacteriocinas.
Assim neste trabalho não foi possível induzir a produção de bacteriocinas em função das condições
testadas.
No futuro seria interessante explorar outras vias de suplementação, como a triptona, ou a criação de um
ambiente competitivo in vitro pondo estas estirpes a incubar juntamente com estirpes patogénicas.
In recent years there has been a greater concern for topics such as physical well-being and environmental sustainability, with a greater demand from society for more “natural” products and more sustainable alternatives, which bacteriocins fit into. They are versatile molecules of natural origin and targeted action and are increasingly proving to be the answer to society's critical challenges, from food safety and preservation to healthcare and environmental sustainability. In this study, 8 strains of Lactiplantibacillus (L. plantarum, L.sakei and L.curvatus) were exposed to various growth conditions in order to cause a situation of metabolic stress and thus produce bacteriocins. Initially, research was carried out on genes that produce bacteriocins. All L. plantarum strains were shown to have several producer genes, while L. sakei strains did not show the presence of any of the genes studied. The Antimicrobial Sensitivity test revealed some worrying resistance to antimicrobials that make these strains unsuitable for human consumption, namely Tetracycline and Penicillin. Under non-stress growth conditions, all strains revealed an inhibitory power not associated with bacteriocins and after growth in modified culture media and protein purification, there was still no inhibition capacity from bacteriocins. Therefore, in this work it was not possible to produce bacteriocins as the growth conditions never created a situation of environmental stress. In the future it would be interesting to explore other supplementation routes, such as tryptone, or the creation of a competitive in vitro environment by growing these strains together with pathogenic strains.
In recent years there has been a greater concern for topics such as physical well-being and environmental sustainability, with a greater demand from society for more “natural” products and more sustainable alternatives, which bacteriocins fit into. They are versatile molecules of natural origin and targeted action and are increasingly proving to be the answer to society's critical challenges, from food safety and preservation to healthcare and environmental sustainability. In this study, 8 strains of Lactiplantibacillus (L. plantarum, L.sakei and L.curvatus) were exposed to various growth conditions in order to cause a situation of metabolic stress and thus produce bacteriocins. Initially, research was carried out on genes that produce bacteriocins. All L. plantarum strains were shown to have several producer genes, while L. sakei strains did not show the presence of any of the genes studied. The Antimicrobial Sensitivity test revealed some worrying resistance to antimicrobials that make these strains unsuitable for human consumption, namely Tetracycline and Penicillin. Under non-stress growth conditions, all strains revealed an inhibitory power not associated with bacteriocins and after growth in modified culture media and protein purification, there was still no inhibition capacity from bacteriocins. Therefore, in this work it was not possible to produce bacteriocins as the growth conditions never created a situation of environmental stress. In the future it would be interesting to explore other supplementation routes, such as tryptone, or the creation of a competitive in vitro environment by growing these strains together with pathogenic strains.
Description
Tese de Mestrado, Microbiologia Aplicada, 2024, Universidade de Lisboa, Faculdade de Ciências
Keywords
Bacteriocinas Stress metabólico L. plantarum L. sakei L. curvatus Teses de mestrado - 2024